Today the rabbis ask a basic biology question. Like many other questions, they answer it through a combination of received tradition, observation and biblical interpretation.
It starts with an earlier discussion explaining that a woman who was raped must be separated from her husband for three months so that, in the event that she gives birth thereafter, the father can be clearly identified. On today’s page, the rabbis question whether a virgin who was sexually assaulted would have to be separated from her husband for these three months because:
Isn’t it known that a woman does not become pregnant from her first sexual act?
It seems to be understood by the rabbis that a woman does not become pregnant from her first sexual encounter, for reasons that will become clear below.
Rav Nahman now notes that this doesn’t mean the assaulter didn’t father a child with her. After all, the woman could still possibly become pregnant by her attacker if she was assaulted twice in a row. The Gemara notes, however, that the language of the case suggests only one assault.
Rava now challenges the assumption that a woman cannot become pregnant from her first sexual encounter, and he does so by examining biblical precedent:
Didn’t Tamar become pregnant from the first act of intercourse?
Let’s review the story. In Genesis 38, Tamar marries Judah’s eldest son, Er. When Er dies before he and Tamar can produce a child, Tamar is betrothed to Er’s brother Onan (her yavam). However, Onan doesn’t want to produce an heir for his brother and “spills his seed” — then God strikes him down as punishment. This leaves Tamar again without a husband or child. There remains only the third brother, Shelah, for Tamar to marry through levirate marriage. But Shelah is too young to marry, so Judah tells Tamar to wait. Time goes by and Judah doesn’t give Shelah to Tamar. Eventually, Tamar takes matters into her own hands, disguises herself as a prostitute and sleeps with Judah — a singular sexual encounter that produces a pair of twins.
The biblical account makes clear that Tamar experienced only one act of intercourse with Judah, which resulted in a pregnancy. So, argues Rava, a woman can become pregnant from her first act of intercourse.
At this point, Rav Nahman might have argued that Tamar was not likely a virgin at the time she slept with Judah because she had been married previously — twice. But instead, he offers a completely different explanation of her pregnancy:
Tamar broke (her hymen) with her finger.
According to Rav Nahman, Tamar broke her own hymen prior to her encounter with Judah to ensure her fertility. (This explains why the rabbis think the first sexual encounter cannot result in a pregnancy — an intact hymen acts as some kind of barrier.)
Now the rabbis ask what many of us have probably been thinking: Was Tamar — who had previously been married to two men — really a virgin when she slept with Judah? The rabbis explain why her marriages to Er and Onan were not fully consummated:
Er and Onan engaged in sexual intercourse in an atypical manner.
Er and Onan, the rabbis understand, did not sleep with Tamar in the “typical” way — which meant that, from their perspective, Tamar remained a virgin after those marriages. Never shy about explaining things fully, the rabbis then engage in a heated debate over what that atypical manner of sex was (anal intercourse? masturbation?) and even delve into the reasons the two older brothers avoided vaginal intercourse (Er thought Tamar’s beauty would be lost through pregnancy, and Onan didn’t want to father a child that would be considered his brother’s).
For the rabbis, the story of Judah and Tamar does not unseat their (wrong) idea that a virgin cannot become pregnant on her first sexual encounter. But their idea that Tamar was a virgin when she slept with Judah shows her to be even more clever and resourceful than we might have realized. What Tamar wants, Tamar gets — namely, an heir (or, indeed, two).
Read all of Yevamot 34 on Sefaria.